It is in your top threading, make sure you are threaded right. When you have it threaded, put the presser foot down and try to pull your thread tail, if it is hard, it is right. Now raise the presser foot and try the same thing, now it will put easily. Another thing make sure you have a fresh needle and that your thread is the same weight top and bobbin. If, all else fails try a SA156 metal bobbin and see if that helps. You can buy them at JoAnns or Walmart. Also on ebay.20 for $8.95 + free shipping and fast service. Good luck. There are other answers but mine is free.
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It is in your top threading, make sure you are threaded right. When you have it threaded, put the presser foot down and try to pull your thread tail, if it is hard, it is right. Now raise the presser foot and try the same thing, now it will put easily. Another thing make sure you have a fresh needle and that your thread is the same weight top and bobbin. If, all else fails try a SA156 metal bobbin and see if that helps. You can buy them at JoAnns or Walmart. Also on ebay.20 for $8.95 + free shipping and fast service. Good luck. There are other answers but mine is free.